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The construction of the Octa calibre has less powerful ties with the history of horology
than the constant-force device or resonance models do. Nevertheless, it symbolizes a horological
ideal: giving timekeepers the highest possible degree of precision and autonomy.
It can be observed, that if church clocks were set so high in towers, apart from enhancing
visibility, was mostly because it often took an entire month for the driving weights to drop the length
of their cords. Numerous systems were invented to increase the running time of timekeeper’s
devices, only meeting limited success. Given the restricted volume of a wristwatch, the size of the
mainspring was immediately limited. Watchmakers then discovered the trick of adding an extra
wheel to the customary gear train, in order to extend the length of its development. Unfortunately,
using this system only led them to observe that the level of energy actually reaching the balance
remained poor. To compensate, they fitted a smaller balance consuming less energy, but which
also lost in stability. Therefore, it’s not unusual to find watches that run for several days display-
ing an extremely unpredictable level of accuracy.
This challenge was a powerful source of motivation. I then imagined that the best and
most obvious solution to lengthen the running time would be to increase the capacity of the
spring development. Given its stability (1 metre and 1 millimetre thick), the challenge was to
integrate it on the same level as the gear train and escapement. Thanks to the low torque of this
spring, I could achieve extremely fast automatic winding (one and a half hour on a Chappuis
cyclotest for over 5 day’s running).
Once the challenge of autonomy was thus successfully met with this automatic winding
calibre, I knuckled down to the second challenge of managing to insert various complications
into that same movement: power reserve with large date display, fly-back chronograph with
large date display, retrograde annual calendar, UTC, etc… and doing so while maintaining
an identical size for all models in the Octa collection.
Three years of research and development were required before this one of a kind auto-
matic calibre could be presented to the public.
François-Paul Journe
Preface
Calibre Octa
A Horological Ideal_
